xargs short-circuit

[Devin Teske]

> -----Original Message-----
> From: owner-freebsd-hackers at freebsd.org [mailto:owner-freebsd-
> hackers at freebsd.org] On Behalf Of Matthew Story
> Sent: Tuesday, February 14, 2012 11:18 AM
> To: freebsd-hackers at freebsd.org
> Subject: Re: xargs short-circuit
> 
> On Tue, Feb 14, 2012 at 2:05 PM, Devin Teske
> <devin.teske at fisglobal.com>wrote:
> 
> >
> >
> > > -----Original Message-----
> > > From: owner-freebsd-hackers at freebsd.org [mailto:owner-freebsd-
> > > hackers at freebsd.org] On Behalf Of Matthew Story
> > > Sent: Tuesday, February 14, 2012 10:35 AM
> > > To: freebsd-hackers at freebsd.org
> > > Subject: xargs short-circuit
> > >
> > > After reading the man-page, and browsing around the internet for a
> > minute,
> > > I was just wondering if there is an option in (any) xargs to
> > short-circuit
> > > on first failure of [utility [arguments]].
> > >
> > > e.g.
> > >
> > > $ jot - 1 10 | xargs -e -n1 sh -c 'echo "$*"; echo exit 1' worker ||
> > echo $?
> > > 1
> > > 1
> > >
> > > such that any non-0 exit code in a child process would cause xargs to
> > stop
> > > processing.  seems like this would be a nice feature to have.
> > >
> >
> > You can achieve this quite easily with a sub-shell:
> >
> > As a bourne-shell script:
> >
> > #!/bin/sh
> > jot - 1 10 | ( while read ARG1 REST; do
> >        sh -c 'echo "$*"; exit 1' worker $ARG1 || exit $?
> >        shift 1
> > done )
> >
> 
> read is often not sufficient for a variety of reasons, the most notable of
> them is that new-lines are valid in file names on most file systems.

Your original example/post neither requested nor implied that such functionality
was required.

If you need such functionality, then you should be using awk, perl, or some
other heavier-lifting code (can even be sh(1), but you'll sacrifice speed).
-- 	
Devin

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